The present invention relates to a spiral compressor of the type having two housing portions one of which has a spiral chamber and a displacement member having a spiral wall extended in the spiral chamber.
Spiral compressors of the foregoing type have been utilized as compressors for Otto and Diesel motors because they are less noisy and less succeptible to troubles than vane-type compressors. While dry-operated vane-type compressors are utilizable only at overpressure up to 0.3 bar because their wear is too high and efficiency is too low the spiral compressors can be used at higher pressure up to 0.7 bar and with substantially better efficiency.
In the spiral compressors of the type under discussion the displacement element must be fixed so that during the rotation of an eccentric of the drive shaft provided in such spiral compressors the displacement element would not be taken along by the eccentric.
In conventional spiral compressors of this type (MTZ 46/1985/9, pages 323, 324), the movement of the displacement element is controlled by an auxiliary shaft driven by toothed belts. This known arrangement corresponds to a two-throw crankshaft parallelogram. To compensate for measurement deviations due to manufacture tolerances and various thermal expansions due to heating of the housing structural components, displacement element and drive, the eccentric bearing of the auxiliary shaft is elastically embedded in the displacement element by a rubber element with predetermined characteristics. The bearings of the auxiliary shaft are grease-lubricated whereas the bearings of the drive shaft are lubricated with oil which is supplied from the oil circuit of the Otto or Diesel motor. This conventional spiral compressor is however expensive in structure and can not operate without a continual lubrication of the bearings with oil. It is not suitable for dry-operations.
Also known is a spiral compressor which has a device for fixing the displacement element against rotation, realized by balls which act similarly to the axial ball bearing and can be held in the bearing rings connected with the displacement element and two housing portions.
In a spiral compressor or pump shown in U.S. Pat. No. 3,817,664 the fixing device of the displacement member against rotation is formed by an Oldham-ring. There the lubrication is also indispensable.